Method of forming passageways extending from well bores



METHOD oF Pomme x'm'ssAcwAYs EXTENDING FROM wm. BoREs: 'I

. evenly dispersed therein.

: B may be omitted.

l'he vehicle D is, preferably, a drilling huid havinga lter loss of lessthan 2' c. c. by the. American Petroleum Institute Standard Test for Filter Ratio of Drilling Fluid.

into the pagsageways O or subsequent-atov the introduction of the vehicle D.

migrate`- to the surfaces-of i. einitial passageways and close most of the smaller-porestheren while some of the 'sealing elements F will also tend to migrate to these' surfaces and seal most of the remaining pores, thus decreasing pressure loss. Conditions, at this point, are sub,-

The vehicle may. be, for example, one, or combinations of,' the drilling fluids described in U`. S. Patents 2,356,776, dated4 August 29, 1944, 2,316,967 dated` April 20, 1943,

` and 2,316,968 dated April 20, 1943, all granted to George Miller. O r it may be the oil-base drilling fluid described by H. W. Hindry in Petroleum Development and Technology, American ln'situte o f Mining and Metallurgical Engineers, 1,941, under Characteristics and Application of Oil Base Mud, pages 70-7 5. Or the vehicle in ay be 'an oil-emulsion drilling uid as described in U. S. Patent 2,430,039 granted to Francis M. Anderson on November The vehicle may be weighed to a desired specific gravity by addition of a commonly-used weighing material, suchas ground barytes.

The pellets E are bodies having substantially no scouring nor abrasive surface area. Preferably,they are bodies having curved surfaces," such as spheres, ovoids andelliposids. 'Ihe'ir diameters may vary. A preferred size of pellet has adiameter or greatest diameter of substantially 0.1"., They are substantially insoluble in the'vehicle D, common well 'uids, and the solvents to behereinafter named. The pellets may be, for example, of glass, plastics or well-rounded pebbles, having no' appreciable abrasive surfaces, and have a specific' gravity which will permit them to float in the vehicle D and be substantially I The sealing elements F may be strips, sheets, flakes, shavings, strands, libres or somewhat analogous forms as have been employed as additions to drilling muds, and my sealing elements are, preferably somewhat pliable, and may be, for example, of (l) polyvinyl acetate; (2) polynitrate or (5 polystyrene. A4Their essential characteristics are that they are relatively slowly soluble in suitable solvents but not quickly soluble in the vehicle D nor in common well uids.

The selection of the solvent or solvents G depends, of

course, upon the composition of the sealing element or elements F employed. Preferably, the solvent is an aromatic hydrocarbon, suitable esters or ketones. For example, for sealing elements of 1, 2 or 5 above, I may employ solvents of benzene, toluene, xylene, acetone, diacetone alcohol, ethyl acetate, or n-butylacetate; for 3 above,

I mayuse acetone, diacetone alcohol, ethyl acetateor methyl aceto acetate, and for 1, 2 or 4 above I may ernploy acetone, methyl ethyl ketone, diacetone alcohol, ethyl the above, for example,having common solvent. In the event I employ the modified composition G, which l contains a vehicle D, pellets E and sealing elements H, but no appreciable volumeof solvent, I may substitute a wider .range of materials for the sealing elements since the characteristics of the sealing elements H do not-require sol ubility. Infact, the commorihuids found within 'wells aridin drilling are, generally such that they do not act chemically toward them. Such sealing elements therefore may be of the same compositions as thejsealiiig elements F and, in addition, may be, for example, of mica,

regenerated cellulose or -cotton seed hulls. r'

In carrying out the steps of one fot-rn of the invention, preferred volumes orweights of vehicle D, substantially like-sized pellets E, sealing elements 'F and solvent for the sealing elements F are, combined as in the reservoir K. andgform the composition' ofmatter C, which ows thru a portion of the conduit system L to the packer A and duit systemic tothe packer A, where it pressures the composition C. Obviously, if te pump M can build up the lrequir'ed pres'sure, the step of introducing the pressure tiuid The introduced'compositionC, under suflicientpressvur,

will be affected as follows: colloids of the vehicle will stantially .as shown in Figure 3. Building up of the pres sure will nallycause th formation of a narrow continuation P of the passageway O (as in Figure 4) since the pressure will force the opposite walls (or one of them) of the initial passageway O apart (or one away from the other). The inrush of the vehicle `D (and-.some of the sealing elements F) into the continuation P will carry some of the pellets E to the mouth of the continuation P-but, because themouth is then narrower than the diameters of the pellets E, the latter cannot enter the continuation but pile up Y f at the mouth, forming a bridge, for example as shown in Figure 4. However, the vehicle may still dow thru the .passageways between the pellets (their curved surfaces, in

contact, forming point contacts and not surface `contacts) and this tends to draw the sealing elements F to the bridge, where they are caught by the pelletsof the bridge and quickly form a seal across the mouth of the continuation` O-. (in some cases this pressure is augmented by further P. As a result dissipation of pressure and the vehicle into -the stratum surrounding the continuation P is stopped and the pressure utilized, instead, in widening the passageway building up the pressure by again employing more pressov methyl methacrylate; (3) cellulose acetate; (4) cellulose acetate, n-butyl acetate or n-a'myl acetate.` Obviously, if' desired, I may employ sealing elements of two or more of are discharged int'o theinitial passageways O with the elements of .the composition of matter C being dispersed somewhat after the showing in Figure 2, whereupon-the yalve l2`l'may be closed `and the valve 22` opened,l per'-Y mittingthe ow of a suit'able pressure lipid as water, oil,

air, carbon dioxide or nitrogen thru' a portion of the consure iiuid.)

rinally, the mouth of the continuation P is widened, by continued pressure upon thewalls of the initial passageway O, to permit the pelletsforming the bridge to enter i the continuation and lodge therealong and this breakage of the bridge will rupture the seal formed by the sealing elements. Pressure upon the vehicle may now be re'V leased. Obviously, by introducing into the vehicle, in the passageway O, a'number of pellets of a larger diameter j than those 'initially introduced,lpermitting them to disperse throughout this passageway O and again building Y uppressure to cause some of them to migrate to the mouth of the continuation P, the bridge andseal may be formed again, a still wider and longer continuation provided, and

the bridge and seal broken as before, since they have then served their purposes.` Sonie of the larger pellets will, of l course, enter the enlarged continuation and lodge therein` I in part supporting its walls, while the smaller (or initially introducedpellets) will migrate further-along the con- 'tinuation and lodge therein, also supporting the walls thereof.

The solvent will, intime, dissolve the sealing elements- Y v The sub-modification of the methodjust disclosed contemplates the introduction of the solvent subsequent to the introduction of a vehiclepellets-sealing elements mixi ture. That is, the solvent may be introduced d uring any subsequent step or even after the last step described. l`his sub-modicationpermits the use of a rapidly-actingsolvent. l .Y A .further modification contemplates the use of a vehicle-pellets-sealing elements mixture or composition following the steps as described-but omitting entirely a solvent furthe lsealing elements. This is the composition G wherein, too, the sealing elements may be of the classes of Amaterials mentioned, including regenerated cellulose and totton seedhulls, `and other suitable materials substantially insoluble in conventional solvents which could composition is desirable', in some instances, because solvents for plastics, particularly such solvents as aromatic hydrocarbons, may also exert a solvent action on some .impair the pore-sealing properties mentioned,

ofthe asphaltic materials in the oil-base muds, tending to l be employed. lPracticing the method, employing this in the moaned-method; a poriiongof the sealing fue."l

ments are driven by lpressure to the outer extremity of the passageway continuation 'where their presence has n'o appreciable undesirable effects) nd the. others 'removed with the vehicleand loose pellets, as by hailing. f it will be' noted that, in the practicingofr any of the several methods described, there is -substantiallytio change iii the integral mass of the stratum surrounding thefbore tially no debris, since the stratum is clovcn or split to'form vthe passageway continuation. In additior i, it will be noted that the pellets not only provide a partial means to close 'during the steps ofthemethod, in that there isstfibstan' f'" the mouth o f thecontinuation but. -without'subsequent mechanical manu` ulation of the pellets, they are caused extendingfrom the initial passageway and having 'a second passageway, and, increasing the passagewayis fractured to provide a second passageway` mouth opening to the initial passageway, c ontinuing pressuring of the mobile body against the opposite walls of'the initial passageway until some of the pellets and sealing elements f oat inthe vehicle to the mouth and the pellets are blocked against entry into the second passageway by the walls' of the initial' passageway at the mouth and pile up at 'the mouth, and some of the'sealing elmentsgare blocked second passageway by the piled-up over the surface of the pile o-f entry of the vehicle into the pressure upon the mobile body within the initial passageway until die second against entry into the pellets and accumulate pellets to form a seal against pellets and at least some of, the sealing elements, which passageway is widened and atleast some ofthe piled-up accumulated 'over the surface of the pile, oat into the second passageway and the pellets therein lodge against the walls of hesecond passageway to prop the walls thereof. .s

' References Cited in the ille .of this patent UNITED STATES PATENTS Y v i 1,807,082 Boynton -2 -2.--- MayZ, 1231 Y 2,245,886A Weir et al. June 17, 1941l 2,264,037 Haskell Nov,A 25, 1941 v 2,272,673 Kennedy Feb. 10, 1.942 2,300,325 Leeuwen Oct. 27, 1942 2,332,822 Williams Oct. 26, 1943 2,337,295 Kennedy Der 21., 1943 2,354,570 Benekenstein July 25, 1944 2,368,424 Reistle, Jr. Ian. 30, 1945 2,379,516 Garrison g.- July 3, 2,398,347 y Anderson v Apr. 16, 1-946 2,476,137 Doll July 12, 1949 Torrey;` P. D.: Selective-.Exclusion of Fluids Froln `Wells The'Oil Weekly, pages 26 to 35, May 22, V1939. l 

